The invention relates to a towing apparatus for a spacecraft when in orbit. The invention furthermore relates to a spacecraft, in particular, a satellite, as well as a towing spacecraft.
The debris created through the ongoing and increasing exploitation of space endangers spacecraft such as, e.g., satellite and manned space vehicles. Generally speaking, spacecraft are supposed to “dispose” of themselves in a controlled fashion before the end of their useful life. However, whenever a malfunction occurs during the lifetime of a spacecraft, conditions may arise whereby disposal of the spacecraft by itself is no longer ensured.
For this reason, certain consideration has been devoted to having defective spacecraft disposed of by special spacecraft, what are called towing spacecraft. To this end, the towing spacecraft must move into the immediate vicinity of a defective spacecraft, e.g., a satellite, and once there dock with a rocket motor or the like. This type of docking maneuver is fraught with difficulties, however, since defective spacecraft are often tumbling. Nevertheless, colliding with the defective spacecraft must be avoided at all costs since then the towing spacecraft itself could suffer damage.
Exemplary embodiments of the present invention provide a towing apparatus that enables a defective spacecraft to be towed simply and more safely. In addition, exemplary embodiments of the present invention provide a spacecraft and a towing spacecraft that enable a defective spacecraft to be towed and disposed of simply and safely.
In accordance with one aspect of the invention a towing apparatus for a spacecraft that may be potentially towed when in orbit is provided. The towing apparatus comprises a cable, the first end of which is permanently connected to the spacecraft, and the second end of which is at least temporarily connectable to a towing spacecraft for the purpose of towing; an attachment piece disposed on the second end of the cable, the attachment piece is mechanically attachable to a complementary attachment piece of the towing spacecraft; and a positioning aid disposed on the cable to allow for detection of the attachment piece by the towing spacecraft. Exemplary embodiments also involve a spacecraft with the towing apparatus. Exemplary embodiments further involve a towing spacecraft comprising an attachment piece mechanically connectable to a complementary attachment piece of a towing apparatus of another spacecraft, the towing apparatus of the another spacecraft including a cable with first and second ends, the complementary attachment piece being disposed on the second end of a cable.
The invention provides a towing apparatus for a spacecraft when in orbit. The towing apparatus comprises a cable, the first end of which is intended to be permanently connected to a spacecraft that must potentially be towed, and the second end of which is provided to be at least temporarily connected to a towing spacecraft for the purpose of towing, wherein an attachment piece is disposed on the second end of the cable for mechanical attachment to a complementary attachment piece of the towing spacecraft, and a positioning aid is disposed to allow for simplified detection of the attachment piece by the towing spacecraft.
The spacecraft and the towing spacecraft are, for example, satellites. However, these can also be manned spacecraft.
The towing apparatus is preferably installed as a preventive measure on every spacecraft to be launched in the future so as to enable this to be towed by the towing apparatus in the event of a malfunction.
The cable provided by the towing apparatus according to the invention allows the towing spacecraft to “dock” with a spacecraft to be towed at a sufficient distance so as to minimize the risk of collision between the spacecraft to be towed and the towing spacecraft. The towing apparatus according to the invention can be installed in a space-saving manner on the spacecraft to be equipped with this apparatus. The action of towing a defective spacecraft furthermore has the fundamental advantage in that any collisions generated by subsequent space debris can be avoided. Provision of the positioning aid on the free end of the cable of the towing apparatus enables the free end to be more easily located by the towing spacecraft. This enables the attachment of the two attachment pieces to be simplified and accelerated.
A mass is preferably disposed on the second end of the cable in such a way as to reduce the tumbling motion of the cable and/or of the spacecraft to be towed. With a spacecraft to be towed, it must typically be assumed that this will undergo a tumbling motion that fundamentally impedes the process of docking to a towing spacecraft. The mass is thus provided on the free end of the cable by which attachment of the towing spacecraft is to be effected in order to increase the moment of inertia of the spacecraft to be towed and retard any tumbling motion. As a result, attachment process is simplified for attachment of the attachment piece to the second end of the cable of the towing apparatus and of the complementary attachment piece of the towing spacecraft. It is especially advantageous for the mass to be provided by the attachment piece and/or the positioning aid itself, since this approach does not require any additional components.
It is advantageous for the cable to be of a length from 5 to 25 m, in particular, from 8 to 12 m, most preferably 10 m, so as to prevent the spacecraft to be towed and the towing spacecraft from colliding during the towing process.
In another embodiment, the attachment piece is in the form of a standardized adapter. This enables spacecraft of varying manufacture to be towed by a towing spacecraft.
In order to facilitate the detection and capture by the towing spacecraft of the free second end of the cable, provision is furthermore made whereby the positioning aid comprises a reflector and/or a permanent magnet. The reflector can be designed to effect optical detection or detection by RF (radio frequency). The reflector and/or the permanent magnet can be disposed on or in the attachment piece of the cable. It is equally possible to provide the attachment piece itself in a form that is reflective and/or magnetic. This can facilitate creating the contact between attachment piece and complementary attachment piece of the towing spacecraft. In addition to creating the connection between attachment piece and complementary attachment piece, provision can furthermore be made whereby another, e.g. releasable locking mechanism is provided that provides a reliable mechanical connection between the two components up to a given force level.
In another advantageous embodiment, the apparatus has a cable receiver that receives the cable in a space-saving manner, and then extends the cable after receiving an actuation signal to attach to the complementary attachment piece in order to enable the spacecraft to be towed. This means that the first end of the cable is mechanically connected through the cable receiver to the spacecraft that must potentially be towed. The cable receiver ensures that the cable is stored in it until the time when a malfunction occurs in the spacecraft. The cable is released by the cable receiver only after the actuation signal is received, with the result that the cable moves away from the defective spacecraft and can be gripped by the towing spacecraft for the purpose of towing and disposal.
To this end, the cable receiver is advantageously connected to a release device that controls the action of extending the cable. In one variant, this device can be operated electrically. Provision is furthermore made whereby the release device has an independent power supply that can implement the action of releasing and thus extending the cable from the cable receiver so as to ensure that the release device functions even in the event of an electrical malfunction in the spacecraft. Alternatively or additionally, it is also possible to operate the release device mechanically. To this end, this mechanism can comprise, by way of example, a spring-loaded mechanism that allows the cable to be extended by the force of a spring once the independent power supply has failed, for example. The release device can preferably be operated both electrically as well as mechanically so as to provide redundancy (i.e., as a fail-safe) for extending the cable.
In addition, the towing apparatus comprises a detection means connected to the release device, the detection means being designed to detect the approach of a towing spacecraft, and in particular, to supply the actuation signal to the release device whenever a certain relative distance has fallen below a specified value, thereby initiating extension of the cable. To this end, the detection means and the towing spacecraft can communicate with each other, e.g., through an infrared interface. The approach of the towing spacecraft can also be detected optically by the spacecraft to be towed. In principle, other variants can also be employed to effect detection of the approach.
The invention furthermore provides a spacecraft, in particular, a satellite that comprises a towing apparatus of the type identified above. A spacecraft according to the invention has the same advantages as those that have been described in connection with the towing apparatus according to the invention.
The invention furthermore provides a towing spacecraft, in particular, a towing satellite that comprises an attachment piece for mechanical attachment to a complementary attachment piece of a towing apparatus of the type identified above, which attachment piece is disposed on the second end of a cable.
In another advantageous embodiment, the towing spacecraft comprises detection means to detect the positioning aid of the attachment piece on the towing apparatus. For this purpose, the detection means of the towing spacecraft can include, for example, a camera or other sensors.